Although projection screens have most commonly been used for movie theatres, educational and industrial image projection, and home entertainment systems, projection screens are finding many new applications related to computer-based simulators and games. These new applications include visual simulations of physical environments, such as race tracks, football fields, battlefields, and airports, in order to provide visual cues to a person interacting with various controls and instruments to control the movement and activities of one or more objects within the simulated environments, such as cars, football players, soldiers and armored equipment, and airplanes.
In certain of the above-mentioned applications, projection of a physical object through an enhanced projection screen towards a person interacting with the computer-based simulated environment can provide added realism and an essentially new dimension to the otherwise 2-dimentional nature of projected images. For example, in a simulation of a martial arts competition, an object thrown by a simulated opponent might be physically projected through the enhanced projection screen from a position on the surface of the enhanced projection screen that coincides with the projected image of the simulated opponent's throwing hand at the point in time that the simulated opponent releases the object. As another example, a simulator used by baseball players for batting practice may project a baseball through a projection screen displaying the image of a baseball pitcher pitching a baseball. Currently-available simulators that involve projection of physical objects from projection screens include one or several fixed locations, or ports, on the projection screen from which physical objects can be projected, greatly limiting the types of actions, such as throwing a martial arts weapon or a baseball, that can be simulated. In addition, the simulated images of the throwers must be unnaturally fitted and positioned so that the release point of a thrown object in the projected image physically coincides with a fixed port on the projection screen.
Alternatively, in certain applications, it may be desirable to use a projection screen that can accept objects. A projection screen may be used as a sorter, for example, behind which bins are placed for the collection of objects that are passed through the screen to fall into different bins. A projection screen that can accept objects is also desirable for entertainment applications. In a football system, for example, users may throw footballs at the projection screen. A passer throwing a football at a virtual receiver displayed on the projection screen can either throw an accurate pass that goes through an opening on the projection screen, or can throw an errant pass that hits the projection screen and bounces away from the projection screen. All such applications are constrained by the fixed position of the openings in currently-available projection screens.
Vendors of simulation and gaming systems have thus recognized a need for a projection screen through which physical objects may be passed at essentially any position on the screen via a movable port. Additionally, vendors of simulation and gaming systems have recognized a need for the ability to synchronize opening of the movable port in time and position with images displayed on the projection screen.